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[HCDX] Is shortwave a short-timer?
Is shortwave a short-timer?
Bill Schweber
(03/07/2008 3:39 A`1/4 EST)
URL: http://www.eetimes.com/showArticle.jhtml?articleID=206902489
The British Broadcasting Corp. recently announced that it would discontinue
its shortwave radio broadcasts to Europe, following the lead of other major
shortwave services. The very mention of the phrase "shortwave" (the
spectrum from about 3 to 20 MHz) brought a nostalgic image to my mind.
Who hasn't seen those old movies
in which listeners are hunched by the radio, straining to hear news from
abroad or perhaps a coded message ("elephants dance under the moon")
while the signal fades, static and interference play havoc, deliberate
jamming intrudes, and the radio drifts and needs retuning?
Shortwave radio is rapidly becoming a museum concept and historical
artifact, right next to telegrams and postal letters. Among the reasons given
by the BBC were a declining audience (an aging one, too, I suspect), the rise
of online news and music, and the cost of running those multi-megawatt
transmitters and their corresponding antenna farms.
The irony is that today's shortwave receiver is far cheaper, smaller and
better than those of just a decade ago. But even those advances can't
overcome limitations on reception and radio schedules.
But before we say goodbye to shortwave, it's worth taking a quick look at
what it has taught us. It popularized low-noise front ends, antenna tuners to
match impedances, dual- and triple-conversion superheterodyne
architectures to optimize stage-by-stage performance and reduce images,
and multiple filters to adapt to different signal modulations, among other
functions. It also provided the platform for developing the PLL-based
synthesized tuner with digital readout, which was far more accurate, precise,
repeatable and stable than older "analog" tuners, along with advances in
crystal oscillator design.
Even better, it taught us about electronics: Until the 1970s or so, you could
build your own receiver from a kit (Heath, Knight and others) and end up
with a fairly sophisticated product that you could troubleshoot and even
modify.
We should keep one more thing in mind before we put shortwave in that
shallow, barely marked grave our industry digs for its castoffs: We may be
prematurely saying goodbye. The BBC pointed out that it will continue
broadcasts to much of Africa and Asia, where Internet access is rare and
costly, despite the intentions of One Laptop Per Child (OLPC) and similar
programs.
Broadcast radio is still a very cost-effective way to reach remote, isolated
and relatively poor regions with news, music and education. Sure, it lacks
the flexibility, depth and broadness of the Web, but it is very real and very
much here. We shouldn't let sophisticated solutions (OLPC and similar) get
in the way of those that already work well for certain audiences and
situations.
Please read my aricle on SINPO at (one line!)
http://zliangas.blogspot.com/2008/02/sinpfemo-better-signal-tech-analysis-
by.html
________________________
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........
Zacharias Liangas , Thessaloniki Greece
greekdx @ otenet dot gr ---
Pesawat penerima: ICOM R75 , Lowe HF150 , Degen 1102,1103,108,
Tecsun PL200/550, Chibo c300/c979, Yupi 7000
Antenna: 16m hor, 2x16 m V invert, 1m australian loop
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